in reply to Tk, fonts and resolution
I use Tk on my Macbook Pro with Retina display. I am not displaying graphic files, but my applications that I wrote over fifteen years ago display fine with no weirdness.
The native resolution of that display is 2880x1800 with pixels that are difficult to resolve with your eyes at normal viewing distances. That's about 220 ppi. So fine details don't pixelate as readily.